maintainers: add kimat

maintainers/maintainer-list.nix

···
     githubId = 59667;
     name = "Ahmed Kamal";
   };
+  kimat = {
+    email = "[e-mail]";
+    github = "kimat";
+    githubId = 3081769;
+    name = "Kimat Boven";
+  };
   kimburgess = {
     email = "[e-mail]";
     github = "kimburgess";